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CBN Grinding Wheels

Vaughn McMillan

Vaughn McMillan

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I had an opportunity this last weekend to go visit FW member Michael James to go offer a few tips and tricks about sharpening his turning tools. Michael has a nice variable speed grinder and a Wolverine jig, but what really caught my attention was his new CBN grinding wheel from D-Way Tools:

http://www.d-waytools.com/tools-diamond-grinding-wheels.html

If I had to sum up the CBN wheel in one word, it'd be AMAZING! He has the 180 grit wheel, and that bad boy was one steel-eating son of a gun, but it did it with such fineness and control, it was a total pleasure to use. I used a super soft touch when applying the tool to the wheel, and got awesome results in seconds. When I get my shop back up in operation, I'll be seriously looking at dropping the coin on one of these wheels for myself. :thumb:

Oh, and sorry, no pics of the meet-up. MJ is in the Witness Protection Program as the result of the freak combination of Watergate, Jimmy Hoffa, and Monica Lewinski, so he's a bit camera-shy. :rofl:
 
I'd love to have one, but they cost way more than my grinder! Do they ever wear out? D-Way has some great stuff. I have a couple of their beading tools, use them a lot and love them. I'd like to have a couple of his turning tools.
 
Paul Douglass said:
I'd love to have one, but they cost way more than my grinder! Do they ever wear out? D-Way has some great stuff. I have a couple of their beading tools, use them a lot and love them. I'd like to have a couple of his turning tools.
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Don't use the price of your grinder as a benchmark. After all, the grinder is just a simple motor. It's the wheel that really makes or breaks the tool. ;) The cost of a pair of good Oneway stone wheels and the Wolverine wheel dresser is more than the cost of a single CBN wheel. And seeing how Michael's 180 grit wheel performed and how fast it removed steel (if wanted), I don't see why anyone would need 80 grit wheel unless they were someone like Doug Thompson putting the initial bevel on hundreds of bowl gouges at a time.

As far as I know, the CBN wheels don't wear out, or if they do, they last much, much longer than a stone wheel. So for someone who turns and sharpens a fair amount, it would potentially pay for itself in the long run. Plus, it puts a very nice edge (very quickly) on a tool. Better (and faster) than I've seen with any stone grinding wheels.

Jim Burr said:
Those are on my radar if I go to a wolverine type system
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I have the parts to set up my Tormek jigs on the dry grinder. I'll eventually get that set up, and when I do, I'll be looking long and hard at a CBN wheel. :thumb:
 
First, bear in mind that everything I am saying is second hand, I haven't used a CBN wheel.

From different manufacturers they are available in various grits from 80 to 220 grit, perhaps others but I haven't heard of them. One warning, according to the threads I have read on the AAW forum, these grits aren't comparable to stones for deciding what wheel to get. A 180 grit CBN wheel cuts as quickly as an 80 grit stone according to reports.

Another consideration is weight. Although some brands are lighter, the eight inch wheel I am interested in is nine pounds! Six inch wheels are roughly half the weight of a comparable eight inch according to one supplier but he didn't have a real number when we were talking on the phone while he was on the road. All are heavier than stones in my understanding. Since you don't need guards all the way around CBN wheels I am considering putting a six inch wheel on my eight inch grinder just to not turn as much weight.

The CBN wheels do have a short break in period, again according to reports. I would expect a very small change in size during this period. After that there is very very little change in size so you can mark the fixtures and jigs you use and basically forget about set-up time. At least one brand of CBN wheel has grit down one side of it for I think about an inch on the eight inch wheels, has the grit on the six inch wheels too but no reports of how far down it goes. Since the heavy aluminum body on the CBN wheels won't break or shatter like a stone there is no risk to side grinding on a near perfectly flat surface. I don't know if the wheels with grit down the side have square or round corners, my guess is square so you might have to consider your usage and decide if round corners or grit down the side is of more value for you. The selling price for all wheels from the company with the side grit is the same but to keep the price the same they don't offer the 220 grit with the abrasive down the side according to a supplier. Perhaps it just isn't offered here, I don't know. The sizes are originally metric on the wheels from Austria I believe, other than shaft sizes I assume, so widths and diameters are slightly different than stated in inches.

The CBN wheels produce very little heat or sparks. Little heat is a nice thing, few sparks means you have to watch very closely to see when sparks are coming over the edge and the tool is sharp when doing pretty large revisions.

A nice thing about the CBN wheels is that they are universally reported to run very true from the factory. The ones from Europe, I think Austria, are wider and heavier than the ones from China. I have to admit, unusually in my opinion, the wheels from China and Austria appear to be equal in quality for all practical purposes. I don't know which is cheaper when you consider the amount of grinding surface on each one. With the life most of us will get out of any CBN wheel it is probably a nonissue.

I have been looking at CBN wheels for about a year now, from the time I started turning. They are nice, but there are some pretty nice stones for thirty to seventy dollars on up to a hundred or more. A fraction of the price of CBN wheels but yet another advantage of CBN is the amount of abrasive dust they don't put in the air. One of those things from working in welding and fabrication, I hate abrasive dust. I hate thinking I always get a little in my lungs and I hate thinking at least a little is getting on everything around where I use a dry abrasive stone. I'm sure there are still some particles off the CBN wheel in the air and breathing in the particles from the steels is none too good for us either but CBN wheels vastly reduce the amount of abrasive in the air and of course eliminate the binder used to hold the stone together.

That's pretty much all I can remember from my reading on CBN wheels and a bit more than I know! :D

Hu
 
OK - I can't refrain any more. I been reading this thread and I am curious.

CBN - Cubic Boron Nitrate

WHY?

I work in Gage manufacturing, down to tolerances as low as 10 millionths of an inch.
We do some "significant" grinding, using a variety of processes.
We grind a host of materials, including D2, Carbide and tool steels.
We DO use CBN - a little bit
We DO use Diamond - where needed
We DO use Ceramic - here and there.
The largest usage though is Aluminum Oxide.

CBN - does not give as good a finish - (per a grinding expert with a Doctorate in grinding technology) - as Aluminum Oxide.

CBN DOES cut faster - but does that mean it is better?
Cutting faster means you have less control.

Having the correct Aluminum Oxide wheel is:
1) Easier to dress and true up
2) Has better friability

Are the home hobby shop people somehow needing better productivity - and longevity.
I can justify CBN in a production shop based on shop rate. dressing time and wheel change time.
It is usually a price per part comparison.

Is there some sort of sales pitch - but value is not "really" there.

Is it because we just want the latest buzzword?

Is there a "real" reason to have CBN in the home shop?

AND

How are you truing up the wheel?
How are you dressing the wheel?

Not trying to be argumentative - just curious.
You can blow me away if you like.

CBN is FAR FAR - NOT - new to me.
I have used and been around CBN - and other stuff you likely don't know about since 1977

I will stick with A. O. wheels

I am also not a turner - though I do DO some turning - and I DO know how to sharpen wood turning tools.

I hope I am not busting any bubbles.
 
Stuart Ablett said:
So the one we want is the "CBN Radius wheel 8" x 1 1/2" - 180 grit" for $220?

Is that right?
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I think the one I used last weekend was the 1" wide model, and I believe it had the radiused corners. I can see some definite advantages to the 1 1/2" wheels, but I did notice I had to be aware of where the Vari-Grind jig was as I was sharpening, since it was easy to touch the jig onto the corners of the wheel if I wasn't careful. I think the wider wheel might compound that problem, although I'm not sure. (And that issue isn't unique to CBN wheels. It'd be the same on any other wheel as well.)

Hu is right about the 180 grit removing steel as fast as a conventional 80 grit wheel. Like I said in my original post, it eats steel, but it's in a good way. I changed the bevel on a skew in a matter of seconds, and yet the finished surface still looked like it has been done on a 180 - 220 grit wheel.

I also concur about the sparks and lack of heat. There were very few sparks, and I saw no signs the metal was getting hot. (The steel still gets hot enough to burn flesh, though. DAMHIKT.) I think part of the reason it doesn't heat the steel as much as some other media, is the fact that you can use such a super light touch when putting the tool to the wheel. Imagine touching a baby's face with your finger as softly as possible. That's about how light I was pressing on the wheel.

As for marking jigs and such for repeatability, the CBN wheel would definitely allow you to do that because it doesn't change size, although I find that lining up the tool's existing bevel on the stopped wheel is still more accurate than a Sharpie or pencil mark on the sliding bar of a Wolverine jig. At one point in the afternoon, Michael started to mark the sliding bar on this jig to remember how I had things set. I convinced him not to bother. For one, he already had several other unidentified marks on the bar, and for two, no matter how carefully it was marked, he'd never be able to line up the mark as accurately as he could simply line up the bevel of the gouge on the wheel. As long as the tool is always put in the Vari-Grind (or other holder) consistently at the same depth (1 3/4" in the case of Michael's set-up) and the angle of the Vari-grind remains the same, the other adjustments are easy to do by eye.

Glad to see there are others getting into selling CBN wheels. Competition in the marketplace can be a good thing. :thumb:
 
Leo, I appreciate "the other side of the story", thank you. I love to turn, and look for reasons to fire up the lathe on most projects. I started with HF tools , have bought some more expensive tools but still reach for my HF tools often. I have a slow speed grinder, with the original, I'm sure "not good" wheels that came with it. I get by pretty darn good. I can look at these other, more expensive accessories, and drool, and often fight the urge to jump. But I do get bu with what I have. Now for a more professional person, that sell or exhibits there work, maybe this stuff is far more important.
 
Leo, to address your questions...

CBN DOES cut faster - but does that mean it is better?
Cutting faster means you have less control.
Click to expand...

Control is in the hands of the guy sharpening. I found I had great control on how and where I was grinding because I could use such a superlight touch. Better than I've had on high-end AO wheels.


Having the correct Aluminum Oxide wheel is:
1) Easier to dress and true up
2) Has better friability
Click to expand...

The CBN wheels being marketed to woodturners never need to be trued, and friability is not needed. Keep in mind, this is CBN bonded to a steel or aluminum wheel. It also doesn't clog up as an AO stone wheel does. And if it does get gummed up from grinding something other than steel, it can be cleaned with solvents or detergents.

Are the home hobby shop people somehow needing better productivity - and longevity.
Click to expand...

Why not? We use electric lathes and power saws to make the process easier, too. ;)

Is there a "real" reason to have CBN in the home shop?
Click to expand...

Sure. For less than the cost of two good AO wheels and an accurate diamond wheel dresser (which, combined, might last a busy turner 5 - 10 years), a person can buy a single CBN wheel that will handle his sharpening needs better, and likely last many years longer. And it never needs to be trued or balanced, and the diameter never changes. All of these things are beneficial to a hobby turner as much as a pro. To me, those are real reasons to own one.

How are you truing up the wheel?
How are you dressing the wheel?
Click to expand...

Not necessary. Runs true out of the box, and doesn't clog, thus doesn't need dressing. ;)

Not trying to be argumentative - just curious.
You can blow me away if you like.
Click to expand...

No worries. You have a legit curiosity as the result of using CBN in a different environment. But as you said, you're not a turner, so some of the appeal of these wheels might not translate to your personal experiences. All I can say (from a pretty well-experienced turner's perspective) is I've never used a dry grinding wheel that gave me as good of results, as easily and quickly, as the 180 grit CBN wheel I used last weekend. And the finish I got was nearly comparable to the finish I get off the 400 grit AO wheel on my Tormek wet grinder. And the CBN wheel costs less than the two Oneway AO wheels (and balancing kit) I currently have on my dry grinder. (And WAY less than my Tormek.)
 
Leo,

Reading your post I suspect you have a far different perspective than most turners. I have worked in R&D. I have machined to tolerances beyond what could be measured with a ten-thousandths mike even splitting between the lines back when my eyes were good enough to split the distance into fifths pretty accurately. I have also pursued rifle accuracy to a level few in the world have chased with the accompanying need for "perfect" machining and fitting. I have hand fit at levels few if any tools can match. All these things make me think that many things said on forums aren't true, and they aren't true when taken to the nth degree. The CBN wheels can be trued to greater accuracy and they can be dressed for example. However, both of these things are wasted effort for the typical woodturner.

The most commonly used wheel by the woodturning community is highly friable, ridiculously so judging by the one on my grinder. It needs regular dressing and rapidly changes size. I just put a wide marker mark on the arm of my sharpening system to get me in the neighborhood because I am going to have to match the tool bevel to the wheel anyway. If I don't chase the wheel size once or twice a day I will significantly change my tool bevel angle.

For the wood turner, the CBN wheels are basically plug and play. There is a cleaning stick but if you just sharpen tools on the CBN wheel using other grinders for rough work you will rarely need to clean CBN wheels and all maintenance on them is near zero. I used a similar metal wheel with the grit soldered/welded to it many years ago, no idea if it was CBN or not but I used those regularly for about five years. Pricey little wheels and when they got dull I threw them away and bought another.

Just a reminder that truth can be situational concerning technical discussion. If you are talking tolerances I once had to hold, many gages were garbage and measuring tools useless for final fit. Much of what I do now that I routinely hold to plus or minus a thousandth would work just as well if I held it to tolerances five or ten times that generous. If you take your thinking from ultra precision work into the wood shop you will be absolutely right in what you are saying but it may not matter in that world.

My primary reasons for wanting CBN are simple, I genuinely hate all the dust those soft white wheels produce, and for our purposes the CBN wheels maintain their size for days and days at a minimum. I will probably make a stop to go on the arm of my sharpening system when I have CBN wheels. Check adjustment in the morning, take seconds to sharpen a gouge each time eight or ten times in a session, maybe two sessions a day, and check my bevel angle when I put up my tools. Using my white wheel I sometimes have to dress it several times a session, resetting all of my sharpening equipment after each time I dress the wheel. If my wheel isn't very close to perfect it is extremely difficult at the least to grind the long perfect sweep I want on the wings of my bevel, sometimes impossible!

With a few exceptions, even master wood turners are amateurs. They have never worked in a production environment with strict guidelines and safety rules, and they have had little or no training other than from other amateurs; granted very advanced amateurs! That often makes the things they state as absolutes drive me a bit crazy as I know they are wrong, anyone who has had any real training knows they are wrong. I mostly hold my peace unless safety is involved and the level of ignorance in that area would make a safety man weep!

('nuther edit, this long post is taking a lot of edits! I want to make it clear I am on a handful of turning forums. The people on these forums aren't the ones I was talking about when I made my comments about people not knowing basic shop practices and safety guidelines!)

Hu
 
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hu lowery said:
...take seconds to sharpen a gouge each time eight or ten times in a session...
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I'm going off on a tangent here Hu, but what kind of gouges are you using? It may be that I'm willing to let an edge dull a bit more than you are before going to the grinder, but with my Thompson gouges I don't generally feel the need to resharpen as often as you're indicating here. For most work (bowls or hollow forms), I generally use a combination of 5 different gouges. I'll often turn all evening with only a single sharpening session at the start of the night. Granted, if I'm using one gouge and feel it's getting dull, I'll often just pick up a sharp sharp one - regardless of the size of shape - and keep turning, instead of stopping to sharpen the dull one. There are some things that I really prefer to use a gouge with a specific profile for, but for a lot of things, I don't really care which gouge is in my hands.
 
Vaughn McMillan said:
I'm going off on a tangent here Hu, but what kind of gouges are you using? It may be that I'm willing to let an edge dull a bit more than you are before going to the grinder, but with my Thompson gouges I don't generally feel the need to resharpen as often as you're indicating here. For most work (bowls or hollow forms), I generally use a combination of 5 different gouges. I'll often turn all evening with only a single sharpening session at the start of the night. Granted, if I'm using one gouge and feel it's getting dull, I'll often just pick up a sharp sharp one - regardless of the size of shape - and keep turning, instead of stopping to sharpen the dull one. There are some things that I really prefer to use a gouge with a specific profile for, but for a lot of things, I don't really care which gouge is in my hands.
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Vaughn,

I'm still using the Crown 5/8" bowl gouge pretty much exclusively. I want to be really confident I can keep the profiles and angles right on my Michelsen gouge made from a Doug Thompson blank before I grind on it. I have used it a few minutes here and there and it needs honing now, not ready to put it on the grinder.

I need to cut a fresh green tree but I'm turning whatever is handy right now. My nice soft sycamore turned to rock in a few months. I can't get much besides sawdust off of that wood. Fixing to burn it. I have some peconcrete that has been drying in the air for eight years too, that pecan would be a good choice to cut steel! Think I'll make a few wedges out of it with the chainsaw and leave it be.

The Crown tool dulls pretty quickly with the profile I am using, sorta a Elsworth/Jamieson/Hu grind. I generally sharpen before starting, then I may need to sharpen once during roughing, once more to finish turn the outside, and several times stretching the length of the bowl gouge trying to hollow well beyond it's reasonably usage with just the straight tool rests I have. It has to be supersharp and me very lighthanded to not have a catch. Trying to order a hollowing system now, had a malfunction with Paypal and getting back to the site. Once the hollowing system gets here I will try rough hollowing with the gouge and finish hollowing with the carbide hollowing tool which can be set to shear cut.

For all of my sharpening I have taken very little off the length of the gouge except when changing profiles. I tried to swap to a Michelsen profile on it too but while the flutes are similar they aren't identical and the Crown won't take a Michelsen grind. The very long wings leave either a very wide nose or more curve to the top of the wings than what I want. One of those things hard to explain, simple when seen.

I haven't kept up but I'm sure all of my sharpenings have removed less than an inch of steel, maybe just a half inch. My whatever is handy blanks have a lot to do with how much I sharpen. Seems I am always cutting petrified wood or half rotten wood that is punky in places and wants to tear out. Either one leads to a lot of sharpening.

Hu
 
Just one note of caution. IIRC one of the drawbacks to CBN vs AO is that the CBN should be used only for magnetic hardened high speed steels, including powdered metal and carbon steels. Other steels and other metals may load up the wheels. I have two grinders, one with two CBN wheels for turning tools and the other, with an AO wheel and a wire brush, for all the other misc grinding I do.
 
Hu - sounds like you have done some tight tolerance work.
Very few machinists ever get there.
We make master rings and plugs as well as a number of other gages.
The gages we measure with are FAR more accurate than tenths mikes.

We are a NIST certified gage lab and can easily measure far below a "tenth".
We make, certify and calibrate master gages here.

Guys - Nope - I am not a turner.
I have turned a bowl and made a couple of spindles and a pile of pens.
I don't have a real big interest in it.

I guess - the world I live in - affects my line of sight.
There is no way the CBN wheels can run true on a bench type grinder, without truing it up.
It is just not possible, given the tolerances between the hole and the shaft on the grinder.
HOWEVER - I am certain it is "good enough", but it would drive me up a wall.

I don't work in a world that most machinists work in.
There is something about the world I am in that once you get used to it - man - .001 then sounds HUGE.
In woodworking - that is seen as - infinity.

OK - I was curious - that's all.
I don't wish to go any further into it than this.

Have fun with CBN ---
 
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